Typical corporate communication systems include a wire line networking infrastructure and an in-building wireless infrastructure. The wire line networking infrastructure is typically packet switched. One example of a corporate communication system is a Group Special Mobile (GSM)/GSM Packet Radio Service (GPRS) network. A packet cellular network infrastructure consists of a Base Station System (BSS) and GPRS Packet Support Nodes (PSN). Currently, a service request is placed at the PSN by a mobile station. Thereafter, the BSS receives data from the service request from the MS and forwards it to the Serving GPRS Support Node (SGSN). The SGSN routes the data towards the destination.
Similarly, the PSN forwards any data received for a mobile station to the BSS. The BSS sends the data to the mobile station. Data from a service request between a mobile station and a fixed station, irrespective of their relative locations, is routed via the BSS, the PSN, and one or more wire line gateways. A similar procedure is used to route data between mobile stations.
This system satisfies the need for wireless telephony and wireless data services. In this system, traffic between mobile stations, such as cellular telephones, and wire line hosts belonging to the same corporate or in-building environment is routed through the corporate gateway, one or more GPRS Serving Nodes (GSNs), and the BSS Packet Control Unit (PCU). This routing, however, does lead to increases in end-to-end delays and packet loss and can lead to poor utilization of expensive transmission resources.
For mobile station-originated data packets in a standardized GPRS system, the BSS does not know the destination of the data packets or the ciphering keys required to decrypt the data contained in the packets. The BSS does not typically know the Temporary Logical Link Identifier (TLLI) to Packet Data Protocol (PDP) address mapping, such as the IP address or X.25 address. In other words, the BSS does not have any routing information to route the data packets.
The current approach for handling Circuit Switched data for in-building applications is to use the GSM recommendations as is, with no special Local Routing capabilities. Consequently, an in-building Circuit Switched data call will be routed up to the MSC and use its Inter Working Function (IWF). Unless special trunk provisioning is performed at the MSC, the Circuit Switched data call will be routed through the PSTN to the in-building PBX for connection to a wired Circuit Switched modem or fax modem. This leads to unnecessary transmissions of data, which in turn leads to delays in reception and inefficient utilization of resources.
Consequently, a need exists for a method for routing data in a communication system that does not increase delays and that fits seamlessly into current communication systems.